Development of a Practical Synthesis of the 8-FDC Fragment of OPC-167832



A concise and practical synthesis has been developed to provide the 8-fluoro-5-hydroxy-3,4-diydrocarbostyril (8-FDC) fragment of OPC-167832 in 41 % yield and in > 99 % purity over 4 steps from 3-amino-4-fluorophenol. The key feature of this process is the development of a telescoped one pot synthesis of the quinolone via a chemoselective amidation and easier product isolation without the need for a column chromatography.